Lesson objectives

Eriochrome Black Indicator reacted with metal ions in water and changed its color:

Eriochrome Black Indicator reacted with metal ions in water and changed its color:

Permanent hardness can be found by deducting the temporary hardness from total hardness i.e.

Permanent = General hardness – Temporary

hardness hardness

GH = TH + RH

CONCLUSION:

The safe drinking water is recognized water:

• with pH of 7 to 7.5 mmol / L
• hardness not more than 7 mmol / L,
• the total amount of minerals in which not more than 1 g / l,
• harmful chemical impurities do not exceed the maximum allowable concentrations,
• and lacking pathogenic bacteria and viruses.